Buffer and delay mechanism for a firearm

ABSTRACT

A mechanism for reducing the recoil force caused by reciprocation of a bolt assembly in a semiautomatic firearm, and for delaying the return of the bolt assembly from its retired position to its battery position. A slide block is mounted for reciprocation adjacent to the barrel, and the bolt assembly is mounted for reciprocation within the receiver. A pair of slide arms are secured to the bolt assembly and extend toward the slide block, normally abutting the latter. A spring engages the slide block to decelerate the latter during rearward reciprocation thereof. The slide block thus decelerates during its rearward stroke while the bolt assembly and slide arms are thus free to move away from the slide block to strike the rear of the receiver and rebound forwardly therefrom. After rebound, the slide arms and bolt assembly strike the rearwardly moving slide block to cause a pause in the reciprocation cycle, after which pause the slide block, slide arms, and bolt assembly all move forward to their original positions under the influence of the spring.

United States Patent 72] Inventor Edwin S. Vartanian PrimaryExaminer-Benjamin A. Borchelt North Haven, Conn. AssistantExaminerStephen C. Bentley [2] Appl. No. 762,593 Attorneys-H. SamuelKieser, Donald R, Motsko, William W. I 22] Filed Sept. 25, 1968 Jones,Richard S. Strickler, Robert H. Bachman, Donald R. Patented y Motsko andThomas P. ODay [73] Assignee Olin Mathieson Chemical CorporationABSTRACT: A mechanism for reducing the recoil force [54] BUFFERAND'DELAY MECHANISM FOR A caused by reciprocation of a bolt assembly ina semiautomatic FIREARM tirearm, and for delaying thbe return of theboll; assgmlglly fLom Mms its retire osition to its attery position. sie 0c is 7 C 5 Drawing Figs. mounted fo r reciprocation adjacent to thebarrel, and the bolt [$2] 0.8. CI 89/130, assembly is mounted freciprocation within the receiver A 89/191, 89/198 89/199 pair of slidearms are secured to the bolt assembly and extend [51] Int. Cl F4ld 5/04,toward the Slide block, normally abutting the m A spring F 41d l1/12engages the slide block to deceleratc the latter during rear- [50] newof 89/130 ward reciprocation thereof. The slide block thus decelerates199 during its rearward stroke while the bolt assembly and slideReferences Cited arms are thus free to move away from the slide block tostrike the rear of the receiver and rebound forwardly therefrom. UNITEDSTATES PATENTS After rebound, the slide arms and bolt assembly strikethe 891,778 6/1908 Mertens 89/ l 99UX rearwardly moving slide block tocause a pause in the recipro- 1,344,991 6/1920 Cunningham 89/191X cationcycle, after which pause the slide block, slide arms, and 1,382,0586/1921 Bourdelles 89/198X bolt assembly all move forward to theiroriginal positions 2,451,624 10/ 1948 Loomis et a1. 89/130 under theinfluence of the spring.

3,2 22 A5 /7ZY f iefl 1:1 1. '1 1 1 r r' 44 P v H I I I 4 1 41 4 Z4 Z420 This invention relates to a mechanism for reducing the recoil forceand therefor increasing the life of the gun caused by the reciprocationof the bolt assembly in a semiautomatic firearm as the bolt assembly ismoved from its battery position to its retired position and returned.The mechanism also provides for delaying the return movement of the boltassembly from its retired position to its battery position to permit agreater time period for the operation of the cartridge extractor ejectorand the feeding of a new cartridge into a position to be picked up bythe bolt assembly and seated in the firing chamber.

The prior art semiautomatic firearms of the type utilizing areciprocating bolt assembly have exhibited several undesirable traitsrelating to the reciprocation of the bolt assembly.

When the conventional bolt actuated semiautomatic firearm is fired, thebolt assembly is driven from its battery position to a retired positionand return. The-bolt assembly, upon reaching the retired position,strikes the rear; face of the receiver thus delivering a recoil shock tothe receiver and shooter; This recoil shock is considerable due to therelatively large mass of the bolt assembly needed to ensure completereciprocation of the bolt assembly. It is desirable to reduce thequantum of shock delivered to the receiver and shooter without reducingthe total mass of the bolt assembly in order to concurrently provide fora more durable mechanism and more comfortable shooting while insuringdependable reciprocation of the bolt assembly.

A second undesirable feature of the prior art bolt actuatedsemiautomatic firearms relates to the time period during which the boltassembly is approximately in its retired position. The time periodduring which the bolt assembly is in its retired position is criticalbecause it is during this period that the fired cartridge casing isejected from the firing chamber and a fresh cartridge is positioned forfeeding into the firing chamber. The bolt assembly must be in itsretired position for a predetermined minimum time period in order toinsure'that these several operations are completely performed. Shouldthe bolt assembly be returned to its battery position before theseoperations are completely performed, jamming of the action of the gunwill occur. Therefore, in order to insure that the specified operationsare completely performed before the bolt assembly is returned to itsbattery position, it is desirable to delay the bolt assembly in oradjacent to its retired position.

The preferred embodiment of the mechanism of this invention includes abolt assembly comprising a bolt slide and a bolt reciprocally mounted inthe receiver of a fireann. A slide block member is reciprocally mountedfor sliding movement beneath and parallel to the barrel of the firearm,the slideblock being acted upon by a gas piston after a cartridge isfired from the gun. A pair of slide arms are connected to the boltassembly and are spring biased into abutting engagement with the slideblock. A return spring is operative to act upon the slide block to biasthe latter toward the gas piston. When the bolt assembly is in itsbattery position, the slide block is disposed adjacent to the gas pistonand the slide arms are abutted against the slide block, so that the boltassembly, the slide block, and the slide arms form an interconnectedmechanism. When a cartridge is fired, the gas piston acts upon the slideblock to impel the latter rearwardly on the gun. The rearward movementof the slide block forces the latter against the slide arms to move theslide arms and the bolt assembly rearwardly toward the retired positionat a first velocity. Thus the initial portion of the reciprocation ofthe mechanism is accomplished with the slide block, slide arms, and boltassembly all moving as a unit. Rearward movement of the slide blockcompresses the slide block spring, which in turn operates to deceleratethe slide block. The bolt assembly and slide arms are not, however,decelerated, and continue to move rearwardly at substantially theirinitial velocity. The resulting difference in respective velocitiescauses the bolt assembly and slide arms to move away from the slideblock, and the slide arms are thus moved out of abutment with the slideblock. The bolt assembly and slide arms continue to move rearwardlyindependently of the slide block until the bolt assembly strikes therear of the receiver and rebounds forwardly. The forwardly movingboltassembly and slide arms then strike the rearwardly moving slide blockand the bolt assembly, slide arms, and slide block momentarily ceasemovement in either direction. The slide block spring then acts againstthe slide block to carry the slide block, the slide arms, and the boltassembly back to their respective original positions. The mass of thebolt assembly and slide arms on one hand, and the slide block on theother hand are chosen so as to cause a halt in the motion of thecomponents upon impact between them. The resultant halt in movementprovides for an extended time period during which the cartridgeextraction and ejection, and fresh cartridge feeding are insured ofbeing fully performed. Also the bolt assembly and slide arms are theonly components of the system which rebound against the receiver, thusthe shock delivered to the receiver and stock, and to the shooter afterthe gun is fired is substantially reduced.

It is therefore, an object of this invention to provide a bolt actuatingmechanism in a semiautomatic firearm wherein the recoil force on thereceiver and that experienced by the shooter from reciprocation of themechanism is substantially reduced.

It is a further object of this invention to provide a bolt actuatingmechanism of the character described wherein an extended actuating timeperiod is afforded to insure that the fired cartridge is extracted andejected, and a fresh cartridge is properly fed into position forchambering.

It is yet another object of this invention to provide a bolt actuatingmechanism of the character described wherein the bolt assembly and slideblock move as a unit during one stage of the actuation, and the boltassembly moves independently of the slide block during another stage ofthe actuation.

It is still a further object of this invention to provide a boltactuating mechanism of thecharacter described wherein the momentum ofthe bolt assembly and the opposite momentum of the slide block areoperative to stop movement of the mechanism for a predetermined timeperiod during-operating of the mechanism. 1

These and other objects and advantages of this invention will becomemore readily apparent from the following detailed description andaccompanying drawings in which:

FIG. 1 is a sideelevationpartially in section of a portion of a firearmincorporating a preferred embodiment of the bolt actuating mechanism ofthis invention, the bolt assemblybeing shown in its battery position;

FIG. 2 is a top view of the slide block taken along line 2-2 of FIG. 1,showing the means with which the slide arms are maintained in abutmentagainst the slide block;

FIG. 3 is a side sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a slide elevation partially in section similar to FIG. 1, butshowing the bolt assembly and slide arms having moved relatively awayfrom the slide block during the actuation of the mechanism and while allthree elements are movingrearwardly on the gun; and

FIG. 5 is a side elevation partially in section similar to FIG. 4.

Referring now to FIG. 1, a bolt actuated semiautomatic firearm, denotedgenerally by the numeral 2, is shown. Various parts of the firearm, suchas the trigger assembly, hammer assembly, and cartridge magazine havebeen omitted for purposes of clarity. It' is understood that aconventional trigger assembly, hammer assembly, and cartridge magazinemay be used with this invention without departing from the spiritthereof. The firearm 2 includes a receiver 4, a barrel 6 connectedthereto, and a stock 8, all of which are of a conventional nature andform no part of this invention. A forearm 10 is mounted on the barrel 6to house the mechanism of this invention. A bracket 12 being hollowedout to contain'a gas chamber 14. A gas bleed port 16 is drilled throughthe bracket 12 and the barrel 6 to provide fluid communication betweenthe gas chamber 14 and barrel bore 18 through which port 16high-pressure gases are bled from the bore 18 into the chamber 14 aftera bullet is fired from the gun. A piston 20 is slidably mounted in thechamber 14, the piston 20 being operable to act upon a slide block 22movably mounted below the barrel 6. The slide block 22 includes a yokeportion 24 and a pair of laterally extending shoulders 26, the latter ofwhich provide abutting surfaces against which the forward ends 28 of apair of slide arms 30 are disposed. Each of the slide arms 30 includes akeyhole slot 32 in which a laterally extending pin 34 is slidablymounted. The underside of the slide block 22 is hol lowed out at 36 toprovide a surface 38 against which the forward end of a return spring 40is disposed. The rearward end of the return spring 40 is seated againstthe front wall 42 of the receiver 4. The slide arms 30 extend rearwardlythrough a pair of slots 44 in the receiver wall 42, and the rearwardends of the slide arms 30 are connected to a conventional bolt assembly46 having a bolt member 47 reciprocally mounted on a pair of rails 48(only one of which is shown) in the receiver 4.

Referring now to'FlGS. 2 and 3, details of the means for maintaining theabutting contact between the slide arms 30 and the slide block 22 areshown with greater clarity. A spring member indicated generally by thenumeral 50 is disposed in the slide block yoke 24, the spring 50including a pair of laterally offset coil portions 52 interconnected bya laterally extending bar 54. The coil portions 52 each are integralwith an upwardly extending finger portion 56. The bar 54 bears againstthe rear face 24 of the yoke 24 and the upwardly extending fingers 56bear against the pin 34 to force the latter against the forward ends ofthe respective slide arm slots 32. The forward ends 28 of the respectiveslide arms 30 are thus forced by the spring 50 against the respectivelaterally extending shoulders 26 on the slide block 22. It will bereadily appreciated that the slide arms 30 are thus not connected to theslide block 22, but rather merely abut the slide block 22.The slide arms30 can be moved away from the slide block shoulders 26 by simplyovercoming the force of the spring 50.

Referring to FIG. 5, the mechanism of this invention is shown during therearward stroke of the bolt actuation after a cartridge is fired fromthe gun. After the bullet passes the bleed port 18 high-pressure gasesare introduced into the gas chamber 14 causing the piston 20 to movetoward the rear of the gun and strike the slide block 22. The slideblock 22 is thus driven to the rear against the slide arms 30 causingthe bolt assembly 46 to move toward its retired position in the receiver4. Thus the slide block 22, slide arms 30, and bolt assembly 46 moverearwardly as a unit during the initial portion of the rearward strokeof the mechanism. Rearward movement of? the slide block 22 compressesthe return spring 40, which in turn tends to slow the rate at which theslide block 22 moves rearwardly. Since the slide arms 30 are not rigidlysecured to the slide block shoulders 26, the resistance of the spring 40is not transferred to the bolt assembly 46 and slide arms 30 exceptnegligibly through the spring 50. Thus, while the slide block 22 isdecelerated by the spring 40, the bolt assembly 46 and slide arms 30continue to move rearwardly at substantially their original velocity. Itis thus readily apparent that a point will be reached during therearward stroke of the mechanism when the bolt assembly 46 and slidearms 30 will move away from the slide block shoulders 26. Such a pointis shown in FIG. 4, the slide block shoulders 26 being spaced apart fromthe forward ends 28 of the slide arms 30.

Referring now to FIG. 5, the mechanism is shown after the bolt assembly46 has struck the rear wall 58 of the receiver 4 and begun to moveforwardly in the direction of the arrow 60 toward its battery position.At the same time the slide block 22 is still moving rearwardly in thedirection of the arrow 62. The slide arms 30 are thus moved toward theslide block shoulders 26 to impact the latter. The rearward momentum ofthe slide block 22 and the forward momentum of the bolt assembly 46 andslide arms 30 are of such magnitude as to cancel each other out atimpact. Thus the bolt assembly 46, slide arms 30, and slide block 22stop movement in either direction momentarily after impact, and sincethe respective momentums are equal and opposite in direction, no recoilis felt by the shooter v shooter, since the momentums are substantiallyequal and in when impact occurs. After the pause in relative movementoccurs, the return spring 40 acts upon the'slide block 22 to return theslide block 22, bolt assembly 46 and slide arms 30 to their respectivepositions shown in FIG. 1.

It will be readily appreciated that the bolt actuating mechanism of thisinvention insures complete actuation of the bolt by providing areleasable interconnection between the slide block, the slide arms, andthe bolt assembly. This permits the individual elements to move as aunit initially in the rearward actuating stroke thereby gaining highmomentum. Subsequently in the rearward stroke, the individual elementsmove separately with one of them rebounding from a rearward surfacebefore the other of them reaches the rearwardmost point of its movement.Thus the actuation recoil delivered to the receiver and shooter resultsfrom a momentum which is one-half the initial momentum of the mechanism,thus doubling the life of the receiver and is, of course, morecomfortable for the shooter. After the actuation recoil occurs, theseparated elements are moving in opposite directions with substantiallyequal momentum. The separated elements then collide with each other withthe result that relative motion in the mechanism stops for apredetermined time period, thus extending the overall duration of theactuation time. It is noted that the collision results in substantiallyno recoil to the opposite directions. The extended period of theactuation time insures complete extraction and ejection of the spentcartridge and feeding of a fresh cartridge into a position forchambering. The mechanism of this invention thus buffers the recoilimpact delivered to the firearm receiver and to the shooter and reducesthe occurrence of jamming during actuation of the bolt.

Since many changes and variations of the disclosed embodiment of theinvention may be made without departing from the inventive concept, itis not intended to limit the invention otherwise than as required by theappended claims.

I claim:

1. In a firearm having a receiver and a barrel secured thereto, a boltactuating mechanism comprising:

a. a first body mounted for reciprocating movement adjacent said barrel;

b. a second body' mounted for reciprocating movement within saidreceiver, said second body including bolt means;

c. elongate means extending between said bodies, said elongate meansbeing secured to one of said bodies and said elongate means being indisplaceable abutting contact with the other of said bodies;

d. gas operated means connected to said barrel, said gas operated meansbeing operable to impel said bodies and said elongate means through anactuation cycle having an initial rearward stroke and a subsequentforward stroke;

e. spring means having one of its ends contacting said first body andhaving the other of its ends contacting a nonreciprocating portion ofsaid firearm, said spring means being operative to decelerate said firstbody during said rearward stroke to thus move said elongate means out ofabutting contact with said other body; and

f. said second body being operative to sequentially strike said receiverand rebound into its forward stroke during the decelerated rearwardstroke of said first body to cause said other body to strike saidelongate means so as to stop relative movement of said bodies and createapause in said actuation cycle, and to prevent said first body fromcontributing substantially to the force of impact imparted to saidreceiver by said bolt actuating mechanism.

2. The bolt actuating mechanism of claim 1, further comprising secondspring means operative to bias said elongate means toward said otherbody.

3. In a firearm having a receiver and a barrel secured to said receiver,a bolt actuating mechanism comprising:

a. first means mounted for reciprocating movement within said receiver,said first means including a bolt assembly;

b. second means mountedfor reciprocating movement adjacent said barrel,said second means abutting said first means; I

0. gas operated means secured to said barrel and operative to impel saidfirst and second means through an actuation cycle having a rearwardstroke and a forward stroke;

d. spring means having one end contacting said secondmeans and havinganother end contacting a nonreciprocating portion of said firearm tobias said second means toward said gas operated means, said spring meansbeing operative to decelerate said second means during the rearwardstroke of said actuation cycle to move said second means out of abuttingcontact with said first means; and

e. said first means being operative to strike said receiver at the endof its-rearward stroke and rebound into said forward stroke, and saidfirst means subsequently being operative to strike said second means toprevent the latter from contributing to the impact imparted to saidreceiver and to create a pause in said actuation cycle.

4. The bolt actuating mechanism of claim 3 further comprising springmeans operative to bias said first means toward said second means. V

5. In a firearm having a receiver and a barrel secure to the receiver, abolt actuating mechanism comprising:

a. a slide block mounted for reciprocating movement beneath said barrel;

b. a bolt assembly mounted for reciprocating within said receiver;

' c. at least one slide arm means connected to said bolt assembly andextending toward said slide block for abutting contact therewith;

d. gas operated means secured to said barrel forward of said slideblock, said gas operated means being operable to impel said slide block,said bolt assembly, and said slide arm means on an actuation cyclehaving a rearward stroke and a forward stroke;

e. spring means engaging said slide block and a nonreciprocating portionof said firearm to decelerate said slide block during its rearwardstroke to move said slide block out of abutting contact with said slidearm means; and

movement f. said bolt assembly being operative to strike said receiverto terminate the rearward stroke of said bolt assembly and to reboundthe latter into its forward stroke, and said slide arm means then beingoperative-to strike said slide block to prevent the latter fromcontributing to the impact delivered to said receiver and to momentarilystop all relative movement of said mechanism to create a pause in theactuation cycle.

6. The bolt actuating mechanism of claim 5, further comprising springmeans operative to bias said slide arm means toward said slide block.

7. In a semiautomatic firearm having a receiver and a barrel secured tothe receiver, a bolt actuating mechanism comprismg:

a. slide block means mounted for reciprocating movement beneath saidbarrel, said slide block means including a yoke and at least onelaterally extending shoulder means;

b. a bolt assembly mounted for reciprocating movement within saidreceiver;

c. at least one slide arm means secured to said bolt assembly andextending toward said slide block means for abutting contact with saidshoulder means;

d. laterally extending pin means traversing said yoke and connected tosaid slide arm means;

e. gas operated means secured to said barrel forward of said slide blockmeans, said gas operated means being operable to impel said slide blockmeans, said bolt assembly, and said slide arm means on an actuationcycle having rearward stroke; first spring means engaging said slideblock to decelerate the latter during its rearward stroke thereby movirg said shoulder means out of abutting contact with sai slide arm means;

g. second spring means engaging said pin means to bias said slide armmeans toward said shoulder means; and h. said bolt assembly beingoperative to strike said receiver to terminate the rearward stroke ofsaid bolt assembly and to rebound the latter into its forward stroke;and slide

1. In a firearm having a receiver and a barrel secured thereto, a boltactuating mechanism comprising: a. a first body mounted forreciprocating movement adjacent said barrel; b. a second body mountedfor reciprocating movement within said receiver, said second bodyincluding bolt means; c. elongate means extending between said bodies,said elongate means being secured to one of said bodies and saidelongate means being in displaceable abutting contact with the other ofsaid bodies; d. gas operated means connected to said barrel, said gasoperated means being operable to impel said bodies and said elongatemeans through an actuation cycle having an initial rearward stroke and asubsequent forward stroke; e. spring means having one of its endscontacting said first body and having the other of its ends contacting anonreciprocating portion of said firearm, said spring means beingoperative to decelerate said first body during said rearward stroke tothus move said elongate means out of abutting contact with said otherbody; and f. said second body being operative to sequentially strikesaid receiver and rebound into its forward stroke during the deceleratedrearward stroke of said first body to cause said other body to strikesaid elongate means so as to stop relative movement of said bodies andcreate a pause in said actuation cycle, and to prevent said first bodyfrom contributing substantially to the force of impact imparted to saidreceiver by said bolt actuating mechanism.
 2. The bolt actuatingmechanism of claim 1, further comprising second spring means operativeto bias said elongate means toward said other body.
 3. In a firearmhaving a receiver and a barrel secured to said receiver, a boltactuating mechanism comprising: a. first means mounted for reciprocatingmovement within said receiver, said first means including a boltassembly; b. second means mounted for reciprocating movement adjacentsaid barrel, said second means abutting said first means; c. gasoperated means secured to said barrel and operative to impel said firstand second means through an actuation cycle having a rearward stroke anda forward stroke; d. spring means having one end contacting said secondmeans and having another end contacting a nonreciprocating portion ofsaid firearm to bias said second means toward said gas operated means,said spring means being operative to decelerate said second means duringthe rearward stroke of said actuation cycle to move said second meansout of abutting contact with said first means; and e. said first meansbeing operative to strike said receiver at the end of its rearwardstroke and rebound into said forward stroke, and said first meanssubsequently being operative to strike said second means to prevent thelatter from contributing to the impact imparted to said receiver and tocreate a pause in said actuation cycle.
 4. The bolt actuating mechanismof claim 3 further comprising spring means operative to bias said firstMeans toward said second means.
 5. In a firearm having a receiver and abarrel secure to the receiver, a bolt actuating mechanism comprising: a.a slide block mounted for reciprocating movement beneath said barrel; b.a bolt assembly mounted for reciprocating movement within said receiver;c. at least one slide arm means connected to said bolt assembly andextending toward said slide block for abutting contact therewith; d. gasoperated means secured to said barrel forward of said slide block, saidgas operated means being operable to impel said slide block, said boltassembly, and said slide arm means on an actuation cycle having arearward stroke and a forward stroke; e. spring means engaging saidslide block and a nonreciprocating portion of said firearm to deceleratesaid slide block during its rearward stroke to move said slide block outof abutting contact with said slide arm means; and f. said bolt assemblybeing operative to strike said receiver to terminate the rearward strokeof said bolt assembly and to rebound the latter into its forward stroke,and said slide arm means then being operative to strike said slide blockto prevent the latter from contributing to the impact delivered to saidreceiver and to momentarily stop all relative movement of said mechanismto create a pause in the actuation cycle.
 6. The bolt actuatingmechanism of claim 5, further comprising spring means operative to biassaid slide arm means toward said slide block.
 7. In a semiautomaticfirearm having a receiver and a barrel secured to the receiver, a boltactuating mechanism comprising: a. slide block means mounted forreciprocating movement beneath said barrel, said slide block meansincluding a yoke and at least one laterally extending shoulder means; b.a bolt assembly mounted for reciprocating movement within said receiver;c. at least one slide arm means secured to said bolt assembly andextending toward said slide block means for abutting contact with saidshoulder means; d. laterally extending pin means traversing said yokeand connected to said slide arm means; e. gas operated means secured tosaid barrel forward of said slide block means, said gas operated meansbeing operable to impel said slide block means, said bolt assembly, andsaid slide arm means on an actuation cycle having rearward stroke; f.first spring means engaging said slide block to decelerate the latterduring its rearward stroke thereby moving said shoulder means out ofabutting contact with said slide arm means; g. second spring meansengaging said pin means to bias said slide arm means toward saidshoulder means; and h. said bolt assembly being operative to strike saidreceiver to terminate the rearward stroke of said bolt assembly and torebound the latter into its forward stroke; and slide arm meanssubsequently being operative to strike said shoulder means tomomentarily stop all relative movement of said mechanism therebycreating a pause in the actuation cycle.